What are some alternatives?
Postman - Postman is the most efficient way to test, develop and document APIs.
Gravitee.io - Gravitee.io is a flexible, lightweight and an open source API management solution.
Apigee - Intelligent and complete API platform
WSO2 API Manager - WSO2 API Manager is a 100% open source enterprise-class solution that supports API publishing, lifecycle management, application development, access control, rate limiting and analytics in one cleanly integrated system.
MuleSoft Anypoint Platform - Anypoint Platform is a unified, highly productive, hybrid integration platform that creates an application network of apps, data and devices with API-led connectivity.
Amazon API Gateway - Create, publish, maintain, monitor, and secure APIs at any scale